There is known a conventional benchmark marking tool including a plate fixed to a structural member of a building through a nailing or screwing working and a benchmark information sheet removably attached to the plate so as to facilitate installation and removal thereof (for example, see Patent Document 1 (Japanese Patent Laid-Open No. 09-089566)).
A plurality of reference points are set to locate structural members in a construction site of a building. For example, when a wall member is located inside the building, one reference point is set on a floor or the like of each floor, and a reference point is set at each position inside the building based on the reference point. Such reference points are called benchmarks, which are important references for determining a position of a structural member during a construction period. Particularly, in a large building such as a power plant which requires a longer time for construction than ordinary houses, the benchmark marking tool needs to be fixed rigidly so as to maintain a benchmark over a long period.
In the conventional benchmark marking tool, the fixing plate is nailed or screwed to the structure of the building. Thus, even when it takes a long time to construct the building, the benchmark can be maintained at a set position over the construction period.
The benchmark marking tool is mostly detached from the structure to be removed during or after completion of the construction working because the benchmark marking tool becomes an obstruction to carriage of equipment into the building or spoils appearance of the structure in the construction of the building. As the benchmark marking tool is fixed to the structure more rigidly, a larger workload is imposed by the removing operation.
In the conventional benchmark marking tool, the structure may crack in a nailed or screwed portion, and a gap is formed between a base material of the structure and the benchmark marking tool, which may result in damage of water tightness of the structure. That is, the conventional benchmark marking tool is not preferably usable for a building of a facility for which high water tightness is required. Particularly, in a radioactive material handling facility or the like including a nuclear power plant, a structure needs to have high water tightness such that a radioactive material attached to a floor surface or a wall surface does not penetrate deep into the attachment portion.
The conventional benchmark marking tool cannot be applied to such a facility.